I just want to know how to do screenshot on this phone? I tried pressing the power button and the volume key but it doesnt work. I even tried downloading an app to do screenshot but when it does, it says "system UI has stopped".

Hi, I'm so sorry because my theme is different, but I need help. My phone, Blackview a8 can't turn on. Firstly, the home page was black and I can't saw my apps. Then, I remove my battery and put it back. The counting of apps started, and after that there is ' starting apps'. My apps can't start, I was waiting for 6 hours.. Can someone help me? Please.